Rare is the flat and unadorned rooftop. Solar companies often face roofs resembling an obstacle course made of vents, pipes and uneven surfaces. What’s a solar contractor to do?
Mounting company SunModo listened to clients asking for a strong system capable of bridging obstructions and putting modules on a single plane, which eliminates shading. SunModo developed the EZHelio SunBeam commercial rooftop mounting system to fill this need.
“Our customers were struggling to find a good racking solution that could be elevated,” said SunModo account executive Brandon Gwinner. “We engineered a solution to meet this basic need, and it turned out to be a huge success.”
By spanning over obstacles, SunBeam takes full advantage of roof space to maximize system size, increasing ROI. Its aluminum construction reduces stress on the building structure while withstanding wind loads and salty air. A heavy duty beam allows longer spans, which reduces the number of posts.
Posts require cutting into the roofing material to the substructure and attaching. Gwinner recommends using the original roofer to apply flashing and boots around the penetration to keep the roof warranty intact.
A California-based contractor used SunBeam on a commercial roof complicated by an air conditioning unit and multiple skylights. The roof pitch was also asymmetrical.
“The SunBeam system made for a smooth and straight-forward installation,” said David Bown, solar consultant at Southwestern Solar Systems. “We were able to easily customize and adjust the racking leg lengths to account for multiple roof pitches on the site.”
Designing a SunBeam system is often a collaboration between installer and the SunModo team. While the components are standard, the number of posts will change due to wind load, snow load, height, tilt degree and obstructions. There is some customization that goes into each project.
“Preferably, a customer will start by sending us a roof diagram with modules,” Gwinner said. “Sometimes they will give me a roof diagram and ask, ‘How many modules can you fit?’”
A 20° tilt will often lead to a layout with modules three, four or five high. A no-tilt system, such as the one at Kauhale Makei Condominiums in Hawaii, can have unlimited modules on a single plane.
Contractors may worry about the effect of putting modules above vents, especially if they’re from a kitchen. Cliff Schrock, solar engineering consultant at SunModo, says 24 in. will probably be enough room for wind to disperse heat. Most vents have deflectors, too. SPW
PV Systems of PR says
This is a great solution for our installations in Puerto Rico. Thank for the info!
PV Systems of PR says
This is a great solution for our installations in Puerto Rico. Thanks for the info!
Ford Eversun says
Its not just the heat from vents that you need to worry about, it is the particulates and potential chemicals (even cleaning chemicals) that you need to worry coming from hood vents, sewer vents, and air conditioners. I have seen over the counter cleaners corrode and erode Aluminum frames to the point of safety concern, not to mention what might happen to the backsheet or leads. Also, I don’t know a module manufacturer that would recommend a tilt less than 5 degrees for shedding water. On the flat modules, water will pool in the middle, along with all of the particulates and in the case of Hawaii, salt. once it evaporates you are left with a large crust of stuff in the middle of your module…which blocks sunlight and reduces power…and in worst case scenarios, causes hotspots in the module and could lead to total module failure. can you clean it, sure…but now you have introduced hardwater or calcium from the hose, which will do the same thing…maybe make it worse.
Don’t get me wrong, I am all about solutions that expand solar potentials, but i would recommend at least a small tilt to the array, and maybe some consideration for the venting. (another reason to tilt to allow convection to drive potentially corrosive vented stuff away from the modules.
SunModo says
Hi Ford Eversun,
You are absolutely correct on both the issue of vents and
the issue of flat mounting of PV modules; however in a simplified article on
the SunBeam we did not discuss these issues in detail.
The SunBeam does allow an elevated array system which can be
very helpful on cluttered rooftops that may include vents, roof conduits, HVAC
units, and other projections above the roof. Access under the arrays for
service of vents, HVAC;s and the roof itself is often a desirable feature and
can be achieved by mounting the SunBeam racking high enough to allow such
access. One does have to be careful to insure that air flows are not restricted
by the PV arrays for critical rooftop outlets. For any vents, and particularly
such as combustion chimneys, kitchen vents, and laboratory vents, each type has
to be carefully evaluated and understood. Some may require a gap in the array;
leaving out a PV panel to uncover the vent, some may require additional routing
of the vent pipe to a point away from or above the array.
On the subject of flat mounting of PV panels, this is not to
mean absolute flat. We recognize that a minimal tilt angle is always required
to prevent pooling of water on the PV panels. Our recommendation at SunModo is
to use a 4 degree minimum tilt which allows the water to mostly flow over the
lower framing on a PV panel.
We would like to thank you for your comments and the
opportunity to share our response with the readers.
Sincerely,
SunModo Team